BEAOA is a new treatment process for efficient deep nitrogen and phosphorus removal jointly developed by BEWG and Academician Peng Yongzhen of the Chinese Academy of Engineering, which has become a powerful tool for pollution reduction and carbon reduction in the sewage treatment process. (Click to learn more about this technology: BEWG and Academician Peng Yongzhen's team developed it!) AOA technology has been successfully applied in 10,000-ton projects)
BEWG tachypellet technology is a new technology product independently developed and created by BEWG based on aerobic granular sludge technology according to the characteristics of China's low-carbon nitrogen ratio sewage water quality, with the core advantages of compactness, low carbon and intelligence, mainly suitable for sewage treatment projects within 20,000 tons/day, and can be quickly applied in scenarios such as decentralized sewage, small and medium-scale urban sewage, industrial point source sewage and sewage in key areas.
In the new era of synergy with pollution reduction and carbon reduction as the key strategic direction, the water treatment industry with high carbon emissions naturally shoulders the burden, and the DNA of carbon reduction of water enterprises is naturally moved, and gradually finds a path to achieve low-carbon in the exploration, such as the utilization of sewage heat energy, refined intelligent control of sewage treatment plants, the combination of sewage treatment plants and photovoltaic systems, the research and development of new sewage treatment technologies, and the energy utilization of sludge. It can be said that the low-carbon path of the sewage treatment industry has gradually become clear.
Sewage heat energy utilization
Sewage heat energy utilization, that is, the application of sewage source heat pumps. The results show that the energy efficiency ratios of ground source heat pumps and air source heat pumps are 3.3~3.8 and 2.8~3.4, respectively, which are lower than those of sewage source heat pumps (3.5~4.6), which indicates that wastewater source heat pumps (WSHP) are more energy-efficient than ground source heat pumps and air source heat pumps, so sewage source heat pump technology has been widely used in sewage treatment energy recovery.
Some places have also clearly introduced policies to encourage the application of sewage source heat pumps. As pointed out in the "Beijing Urban Management Development Plan for the 14th Five-Year Plan Period", it is necessary to make full use of waste heat resources. Promote the pilot transformation of waste heat utilization and transformation of thermal power centers in the northeast and southeast. Gradually reduce the return water temperature of the urban heat network and improve the utilization efficiency of waste heat in power plants. Promote the recovery and utilization of waste heat from gas boiler rooms and data centers, and replace sewage source heat pump heating in areas where conditions permit.
A number of leading enterprises have deeply recognized and taken the lead in practicing the substitution of sewage source heat pump heating.
Li Li, executive president of BEWG, said that the water source heat pump in the sewage treatment plant can further develop and utilize "water energy" while utilizing water resources, which will make a great contribution to carbon reduction.
Capital Environmental Protection In the Chengnan Sewage Treatment Plant in Taiyuan, Shanxi Province, the treated sewage is used as a cold and heat source, and the water source heat pump unit is used to cool and heat the buildings in the factory area.
Everbright Water has also practiced wastewater source heat pump projects.
100% of the sewage of the Central Water Guiyang Project is reused, and after deep treatment, 20% is used as high-quality reuse water, and 80% is discharged into the river as ecological water replenishment; At the same time, the sewage is lifted to the water source heat pump system through the water pump for cold and heat utilization, which can provide heating and cooling for the ground complex, and achieve clean function and low carbon emissions.
However, this technology is not perfect, and it also has shortcomings, experts pointed out that the residual temperature heat energy contained in sewage can only be converted into a low-grade heat source of about 60 °C through the water source heat pump, and cannot be directly used for power generation, which limits the application and promotion of this technology.
Sewage energy conservation and consumption reduction
Wastewater energy conservation and consumption reduction, that is, refined and intelligent control of sewage treatment plants. According to incomplete statistics, the power consumption of sewage treatment plants can be reduced by 10% or more (mainly for aeration pipe systems) through refined intelligent control, and the chemical dispensing rate can be reduced by more than 30% or even higher (mainly for carbon source dosing).
According to statistics, in the urban sewage treatment plants established in our country, electricity and dosing costs account for more than 50% of the cost of sewage treatment. Therefore, under the premise of meeting the discharge standards, sewage treatment plants urgently need to implement optimized operation to achieve the goal of energy conservation and consumption reduction.
In response to this, recently, the team of Professor Shi Hanchang of the Institute of Environmental Engineering of the Beijing-Tianjin-Hebei National Technology Innovation Center proposed a STEM model (Sewage Treatment Engineering Model) for sewage treatment engineering. The model is closely combined with the actual operation characteristics of the sewage treatment plant, and the model correction analysis can be carried out by using the conventional index data of the sewage treatment plant. Specific applications include process simulation, precise aeration, intelligent dosing, and optimized operation expert systems, which can effectively achieve the optimal operation of sewage treatment plants and achieve the goal of energy conservation and consumption reduction.
Another example is the intelligent system transformation project of Yantai Taoziwan Sewage Treatment Co., Ltd., which was recently shortlisted for the Smart Water Project of the Year in the "2022 Global Water Awards (GWA 2022)", which includes the main functions of online early warning and prediction, plan management, intelligent dosing, equipment management, and log reports; On the basis of water quality early warning and forecasting and plan management, optimize and control the dosing of denitrified carbon sources, and reduce the cost of carbon source dosing on the basis of ensuring that the water quality meets the standard. The carbon source input has been reduced by 10% year-on-year, and carbon emissions have been reduced by 231t (CO₂equivalent). Save nearly 1 million kWh of electricity and indirectly reduce carbon emissions by 1,000 tons (CO₂ equivalent), so as to achieve the goal of energy conservation and consumption reduction of the sewage plant.
The sewage plant is combined with the photovoltaic system
In April 2020, five national ministries and commissions issued documents to encourage sewage treatment enterprises to comprehensively utilize site space and adopt the "spontaneous self-consumption, surplus online" model to build photovoltaic power generation projects.
In November 2021, the Zhejiang Provincial Energy Bureau officially issued the country's first provincial implementation guidelines for promoting the pilot work of distributed photovoltaic development in the whole county. The document clearly states that the photovoltaic installation ratio of existing sewage plants and waterworks is required to be more than 90%, which has become one of the key tasks for distributed photovoltaic development.
Professionals believe that if more than 4,000 sewage treatment plants across the country can build an average of 5 megawatts of photovoltaic power plants per sewage plant, the scale of photovoltaic power plants that can be built by these sewage plants will exceed 20 GW. In order to improve the efficiency and quality of sewage treatment, more and more sewage plants have begun to explore the mode of photovoltaic power generation, and the CP of sewage treatment plant + photovoltaic power station is also increasingly appearing in the public's field of vision, and it is likely to explode. ("Water and light CP" continues to appear: these sewage treatment plants have put on photovoltaic cloak)
On the one hand, it reduces the impact on the power quality of the power grid, reduces the business disputes with the power operation company when grid-connected power generation feeds power to the grid, and on the other hand, it can make full use of the state's policy subsidies for new energy distributed generation to reduce electricity costs to reduce electricity costs.
Many industry leaders have also made great achievements in this regard.
For example, the Yangtze River protection project led by the Three Gorges Group has been combined with photovoltaic projects many times: the first phase of the distributed photovoltaic project of Wuhu Zhujiaqiao Sewage Treatment Plant has been connected to the grid in September 2020; The distributed photovoltaic project of Wuhu Chengdong Sewage Treatment Plant began generating electricity in September 2021; The Gao'an Sewage Treatment Plant in Sanshan District, Wuhu City was officially connected to the grid for power generation in early November 2021, and the other four planned sewage plant distributed photovoltaic projects will be put into operation one after another. The planned total installed capacity of these seven sewage plant distributed photovoltaic projects in Wuhu City is about 20,000 kilowatts, and it is expected that it can provide an average of about 23 million kWh of clean electricity to the power grid per year after completion, which can save 7,200 tons of standard coal per year, reduce the emission of sulfur dioxide by about 0,700 tons, and carbon dioxide by about 19,700 tons compared with thermal power.
Energy-saving Guozhen, which operates the super photovoltaic power plant of Wang Xiaoying Sewage Plant, also said on the investor interactive platform that most of the company's sewage treatment projects in Anhui, East China, South China, Central China, Northwest China, North China and other regions have the conditions to add distributed photovoltaic projects.
Wuhan Holdings has built the largest distributed photovoltaic power generation project of the sewage treatment plant in the country - the distributed photovoltaic project of Beihu Sewage Treatment Plant. It is estimated that after the Beihu photovoltaic power generation project is connected to the grid for power generation, it can provide about 22 million kWh of green and clean electricity per year during the 25-year operation period; It saves about 8,000 tons of coal for power generation, which is equivalent to reducing carbon dioxide (CO2) emissions by about 20,000 tons, with outstanding environmental benefits and significant energy conservation and emission reduction effects.
Everbright Water's sewage treatment project in Zibo, Shandong Province has launched a pilot project of in-plant photovoltaic projects. The photovoltaic facility was connected to the grid in August 2021 and is expected to generate 9% of the electricity consumption of the project site, accumulating good experience for future on-site photovoltaic pilots.
With the gradual increase in the requirements for pollution reduction and carbon reduction, the two-in-one sewage + photovoltaic is no longer the most powerful, and three-in-one projects have also appeared.
A few days ago, the second phase of the Xianju County sewage treatment project contracted by the EPC general contractor of the East China Survey and Design Research Institute won the 2020-2021 National Quality Engineering Award. This new conceptual sewage treatment plant integrates sewage treatment, wetland park and photovoltaic power generation, providing residents with a water-friendly park for popular science education and leisure tours while serving the needs of sewage treatment, and providing vivid practice for high-quality green development. (Sewage treatment + wetland park + photovoltaic power generation three-in-one!) This sewage treatment plant won the National Quality Engineering Award)
Recently, Liaocheng Water Wastewater Treatment Co., Ltd. started construction of the 2.13MW distributed photovoltaic power generation project, which intends to use water source heat pump technology to recover heat energy and organic matter energy in sewage to achieve comprehensive energy utilization, creating a precedent for the application of sewage treatment plant + photovoltaic + comprehensive energy in the province.
Path 4 Research and development of new sewage treatment technologies
In this regard, industry leaders led by BEWG, Guangdong Haihai Water, Capital Environmental Protection, Bishuiyuan, and Energy Conservation Guozhen have taken the lead and achieved successful application.
BEWG has newly released BEAOA and BEWG tachypranulation technology, among which BEAOA has successfully carried out 100-ton pilot and 10,000-ton in-situ transformation project application practice.
Relying on the achievements of Academician Ma Jun's "Key Technology of Gravity Flow Direct Ultrafiltration Water Purification", Guangdong Sea Water Affairs has carried out the application exploration of modular assembly water purification plants.
The mathematical simulation technology of sewage biological treatment and CREATE aerobic granular sludge technology independently developed by Capital Environmental Protection Group can reduce carbon source input by more than 50%-70%, save electricity consumption by 25%, reduce operating costs by 35%, and save building land by 50%.
The newly developed vibration MBR technology has been successfully applied to the Doudian Water Reclaimed Water Plant, which reduces the aeration demand and energy consumption of the wastewater treatment process. For the Doudian Reclaimed Water Plant with a daily treatment capacity of 15,000 square meters, it can save nearly 400,000 yuan in electricity bills a year, and the total nitrogen in the effluent is less than 5mg/L, and it can produce more than 5 million cubic meters of high-quality reclaimed water a year. At present, Bishuiyuan Company has put into use or plans to put this technology into use in Beijing and other places, with a cumulative daily sewage treatment capacity of 500,000 square meters, which can save about 13 million yuan in electricity bills every year.
Recently, CECEP's "AAO process high-standard urban sewage treatment low-carbon integrated technology" was evaluated by experts from the appraisal committee and unanimously determined that the technology has reached the international advanced level. After third-party testing, after the use of this technology, the emission index of the main pollutants in the effluent has stably reached the surface water class IV standard, the energy consumption per ton of sewage treatment plant has been reduced by 8%-16%, the consumption of water agents (phosphorus removal, carbon source) per ton of water has been reduced by 15%-50%, the direct operating cost has been reduced by 10%-20%, and the emission of CO₂ has been reduced by more than 10%. At the same time, the coordinated sewage treatment operation and management effect of energy conservation and consumption reduction, pollution reduction and carbon reduction has been realized.
Path 5 Energy utilization of sludge
The energy utilization of sewage treatment by-product sludge is the use of biogas for anaerobic digestion and the heat energy utilization of incineration.
At present, the selection of sludge treatment and disposal process in our country is mainly based on technical applicability and economic cost. Considering the future carbon peak and carbon neutrality goals, carbon emissions, as one of the important indicators for the selection of sludge treatment and disposal routes, are the future development trend.
It is reported that the carbon emissions of the sludge anaerobic digestion process are relatively low, and it has the possibility of achieving negative carbon emissions. The sludge anaerobic digestion coupled biogas cogeneration project can realize the recovery of heat and electricity and improve energy efficiency. At present, sludge cogeneration has been applied to many projects in our country and has achieved obvious carbon emission reduction effects.
Shanghai Bailonggang Sewage Treatment Plant adopts a medium-temperature anaerobic digestion system, with a treatment scale of 204 tons of total dry sludge per day, and a biogas output of about 40 000 cubic meters/day. The excess biogas can also be used for the heat demand for partial sludge drying.
BEWG's Beidaihe New Area Sludge Treatment Plant project has a daily treatment capacity of 300 tons (80% moisture content), and the treatment process adopts a fractional/split-phase anaerobic digestion process.
Dai Xiaohu once pointed out in the paper that dry incineration belongs to the moderate carbon emission level, focusing on the development of efficient and low-consumption deep dehydration technology and environmentally friendly dehydration agents, reducing the energy consumption of sludge drying, reducing the impact on coking and fly ash in the subsequent incineration process, and improving the rationality of process design and the overall intelligent integration level. From the perspective of future development, anaerobic digestion-drying incineration process is expected to become an important development direction for sludge treatment and disposal.
epilogue
During the "14th Five-Year Plan" period, our country's ecological civilization construction has entered a critical period of carbon reduction as the key strategic direction and promoting the synergy of pollution reduction and carbon reduction.
Resources:
1. "Carbon Reduction Methods for Sewage Treatment Plants under the Situation of Carbon Neutrality" Environmental protection I will help you
2. "Interview with Li Li, Executive President of BEWG: "Synergy of Pollution Reduction and Carbon Reduction" Brings New Transformation Opportunities, and Environmental Protection Enterprises Need to Take the Road of Light Assets" Daily Economic News
3. "Dai Xiaohu et al.: Thoughts on the Development Direction of Sludge Treatment, Disposal and Resource Utilization under the Background of Carbon Neutrality" Water supply and drainage
